Field of the Invention
The present invention relates to a combustion apparatus, and more specifically to a combustion apparatus configured to supply combustion air from outside a combustion chamber thereinto as a combustion fan draws the air internal to the combustion chamber.
Description of the Background Art
A combustion apparatus of a type combusting an air-fuel mixture of combustion air supplied by a fan motor and gas or a similar fuel maintains a satisfactory combustion state by controlling an air fuel mixture ratio (or an air fuel ratio) to have a prescribed proper value. Generally, depending on the quantity of heat requested to be generated, the quantity of fuel is controlled, and depending on the quantity of fuel as controlled, a combustion fan is controlled in rotation speed to maintain a proper air fuel ratio.
With combustion thus controlled, Japanese Patent No. 4656442 discloses controlling a forced air supply type combustion apparatus for maintaining a proper combustion state when the combustion apparatus has an air supply/exhaust path clogged. According to Japanese Patent No. 4656442, when the air supply/exhaust path is clogged to an increased degree, a gas proportional valve is energized with an increased current for correction to prevent gas from being supplied in a reduced quantity. According to Japanese Patent No. 4656442, when the combustion fan has a constant rotation speed, and the air supply/exhaust path is clogged to an increased degree, the fan current increases, and this phenomenon is exploited to calculate from the fan rotation speed and the fan current to what degree the air supply/exhaust path is clogged.